Merc 140 Trim Issues - Very Strange, Please Help

[swihartart]

1977 Starcraft I/O. Tri-Hull 140 Merc.​

I am trying to fix up my new old boat. After having it out for the second time, hit a sand bar. A small hole in my trim cylinder appeared. I decided to work on the trim system since the rams looked old and pitted to begin with as well as the lines looked old (cloth style). Rams were patched many times.​

I replaced the bottom assembly of the Prestolite Pump. It just screwed right to the bottom of my reservoir around the perimeter. (6 or 8 screws) Mine blew one of those small o-rings on bottom of "dog bone" just after the port cylinder started leaking where it was patched.​

Also bought 2 "working trim rams" fom Mike's Alphas on Ebay. They appear to be in good shape. He also sent 4 stainless lines for outside and a distribution block.​

Bought 2 new lines. Black for up side of pump. Grey goes from reverse lock to block.​

After installing everything, here is my problem.​

Port side ram will go down but not up.????? It will move slightly but then stops. Coming back down no problem.​

Starboard side: Up goes slow, pump sounds strained. Down no problem.​

I took one of the old rams that was not leaking and swapped out the starboard ram and it does the same thing.​

I bled the system several times while keeping it topped off with the rams in.

Trim Rams are not connected to back pin during this problem. Been reading. Could a trim limit switch be the problem????? Manual says to disconnect rams to perform bleed procedure.

Ant ideas are greatly appreciated.​

 

[picklenjim]

Re: Merc 140 Trim Issues - Very Strange, Please Help

Try this. Remove the UP line from one of the cyls. and hit the switch up to be sure you have a good flow coming out of the line. Reconnect and then remove the DOWN line from that same cyl..If you remove from the junction block end you can direct the fluid into a bucket.Now with the DOWN line off run the pump up.Care full fluid is going to come out of the disconnected down line.When the cyl. is fully extended reconnect the DOWN line.Run the cyl.all the way down. Now repeat this on the other cyl.Now run them up and down a few times. If the cyls. still have a hard time going up but not down then you have a valve problem in the pump not allowing fluid to flow back to the pump from the down side.Be sure to keep reservoir full at all times.Motor oil is what's recommended and works best in these pumps.Trim limit switch has nothing to do with this beings you have rams disconnected.Limit switch shut off power to the pump at a designated trim height so you don't over trim then raises the rest of the way with the trailer switch.

 

[swihartart]

Re: Merc 140 Trim Issues - Very Strange, Please Help

Thanks Jim, Will do and post back what I get.

I may try to swap the new "dog bone" on pump with my old pump since the new has the o-rings I need. Old pump worked fine, just blew that o-ring. (Age????)

Maybe a faulty pump was sent. He (Mike's Alphas) told me not to take "dog bone" off bottom of pump cause I can't get new o-rings and I probably lost small pieces when I took off my original "dog bone". I didn't notice any small pieces, I just removed the 4 bolts to inspect why it was leaking. It was the o-ring that ripped that caused the leak. Was just gonna find another o-ring but for $75 for a used bottom part of pump, I went this route.
He guarantees the parts so if I swap the "dog bones" and my old pump works with new o-rings, the pump must be bad.

I called him and he seems to think it is the reverse lock and recommends I buy a newer pump upgrade and says that all I need to change are the lines that go to the block if I upgrade. I visited a marine mechanic and he thinks this CANNOT be done. He claims you must change the trim cylinders also if you upgrade to pump (oildyne?) with reverse lock built in.

Now I'm really confused!!

I will try your suggestion first though. Thanks again for your help. Hope I can get it out one more time before PA winter steals my first year of boat ownership.

I'm currently reading HEAVILY on winterization to get ready for next year.
Thanks Don for the manual.